German Printed Patent No. 29 01 504 explains that, in order to park in a parking space, one must first measure the length of the parking space when driving by, so that dependent upon the motor-vehicle's position and the length of the parking space, the motor vehicle can be parked with as few steering movements as possible. To the extent this is possible, no available parking space will remain unused and as many vehicles as possible can park.
However, such a parking method cannot be used for maneuvering a motor vehicle out of a parking space, since when one starts to maneuver a motor vehicle out of a parking space, the length of the parking space, i.e., the available path in front of and behind the motor vehicle to maneuver out of the space, is not known. Even storing the dimensions of the parking space measured during the parking operation does not solve this problem, since the size of the parking space can change while the vehicle is parked. Also, when one starts to maneuver a motor vehicle out of a parking space, neither the distance from the motor vehicle to adjacent motor vehicles and other obstacles, nor the width of those obstacles, is known and, thus, an optimal steering angle is unable to be determined.
Therefore, the strategy used during the parking operation--to park the motor vehicle as close as possible to the curbstone and utilize the smallest amount of parking space possible--cannot be applied when maneuvering a motor vehicle out of a parking space.